In the 1960s the CIA spent over $20 million for an operation called Acoustic Kitty. The operation consisted of turning a cat into a spy in order to help the US Federal Government receive information about Kremlin and the Soviet embassies.
The very first spy kitty was implanted with a battery and a microphone with a receiving antenna in its tail. It was supposed to eavesdrop on two unnamed men in a park just outside the Soviet Compound in Washington. The trained and equipped cat was released on field work but, allegedly, it got hit by a taxi and died. Robert Wallace, the former Director of the CIA’s Office of Technical Service, denied it explaining that the cat had been freed from the mechanical equipment because the training itself was too difficult and unpromising. According to Wallace the cat lived a long and happy life after it had been cut and re-sewn for the second time.
In 1967 the project was cancelled for lack of any successful subsequent tests.